Applicant has published a lamp base of this general type in her product catalog “LED Bridging” on page 30 as article number 28.107. The holder recited therein receives a lamp base which is fixated by a bayonet type insertion and rotation movement. The housing for the lamp holder is configured in two components, wherein an inner holder housing component is moveable relative to an outer holder housing component. Attachment devices configured as threaded bolts retain coil springs supported between both housing components, wherein the inner housing component is liftable against a reset force of the coil spring during fixation of the lamp base through locking cams. An embodiment with the product designation 28.301 on page 34 of the catalog recited supra illustrates a configuration that is similar in principle. Different from the prior embodiment this embodiment has a one piece housing. Also here coil springs supported by the shaft of the threaded bolt are supported at the holder housing on one side and at a head of the threaded bolt on the other side. Also here the lamp base lifts the holder housing against reset forces of the coil springs during fixation of the lamp base in the holder.
The coil springs generate a force upon the lamp base which presses the heat conducting element against the lamp component so that the surface pairing of heat conducting element and lamp component is subjected to a uniform and defined contact pressure. This contact pressure facilitates heat transfer from the lamp to the lamp component optionally using additional heat transfer devices like heat transfer paste or heat transfer foil wherein the lamp component is typically used as cooling element or explicitly configured as cooling element. Providing heat dissipation is of great importance in particular when using lamps that are provided with LEDs. Only sufficient heat dissipation provides a long service life for the lamp.
In order to prevent damaging the holder element when attaching the recited lamp holders of the applicant at a lamp component, non standard threaded bolts are used whose threaded shaft transitions into a bolt shaft through a diameter enlarging contact shoulder. This assures that the threaded bolt shaft can only be threaded into a corresponding threaded bore hole up to a defined depth. Accordingly the threaded bolt is sized so that the holder is correctly attached at the lamp component but not damaged by the tightening torque.
Holders with one piece housing of this general type are known in the art and not included in any printed document, wherein attachment openings of the holders are penetrated by a hollow rivet. The base housing is moveable relative to the respective hollow rivet. A coil spring element is inserted between the head of the hollow rivet and a stop configured by the housing in the attachment bore hole, wherein the coil spring element applies the advantageous preload upon a heat conducting element of an applied lamp base. In order to provide attachment at a lamp component a threaded bolt is run through the hollow rivet, wherein a head of the threaded bolt contacts the head of the hollow rivet in order to limit the threading operation and in order to limit the tightening torque, whereas the base of the hollow rivet is supported at the lamp component.
The recited embodiments have proven suitable in practical applications, but there is a long felt need for improvement for particular applications. It has been found to be advantageous when the spring element is preloadable already during mounting of the holder in order to increase heat transfer improving contact forces between the contact surfaces of the base side heat transfer element and the lamp component. From a production cost point of view it is desirable to be able to use standardized attachment elements which are cheaper to manufacture and which are easier to handle when applying the spring preload.